NICET Special Hazards cheat sheet

Clean agent systems (NFPA 2001) use halocarbon or inert gas for total flooding; selection depends on occupied-space safety, enclosure volume, and hold time.

CO2 systems (NFPA 12) extinguish by oxygen displacement and cooling; total-flooding designs can be lethal to occupants and require strict safeguards.

Wet chemical systems (NFPA 17A) protect commercial cooking appliances by saponifying fats and oils; nozzles cover cooking surfaces, hood plenums, and exhaust ducts.

Dry chemical systems (NFPA 17) use ABC or BC powders to break the combustion chain; they are effective on flammable liquids and gases but leave cleanup residue.

Foam systems (NFPA 11) form a blanket over flammable liquids to separate fuel from air and suppress vapor; low-, medium-, and high-expansion foams have different application rules.

Water mist systems (NFPA 750) use fine droplets for cooling, oxygen displacement, and surface wetting; pressure class determines nozzle and component requirements.

Water spray systems (NFPA 15) apply water directionally from fixed nozzles to specific hazards such as transformers, tanks, and process equipment.

Foam-water systems (NFPA 16) combine a foam blanket and water cooling through sprinklers or spray nozzles for flammable liquid fire protection.

Clean agent total-flooding quantity is calculated from enclosure volume, design concentration, agent specific volume, temperature, and altitude using NFPA 2001 and listed manufacturer data.

Enclosure integrity: the room must retain the design concentration for the required hold time; door-fan testing quantifies leakage and identifies openings.

Cross-zoned detection requires two independent detectors to alarm before clean agent discharge; this reduces false discharge while preserving detection speed.

Agent discharge piping and nozzles must follow the listed design; nozzle spacing, height, orientation, and coverage cannot exceed manufacturer limits.

Wet chemical nozzle layout must cover all cooking appliances, hood plenums, and exhaust ducts, and must include fuel/power shutoff and manual actuation.

Foam design selects application rate, foam concentration, and discharge duration from NFPA 11 based on fuel type, storage arrangement, and foam concentrate listing.

Water mist pressure classification: low pressure is up to 175 psi, intermediate is 175 to 500 psi, and high pressure is above 500 psi per NFPA 750.

Pipe sizing for gaseous and foam systems uses hydraulic flow calculations; pipe supports, backflow prevention, and hydrostatic testing follow the adopted standard.

Monthly inspection covers gauge readings, cylinder condition, valve position, alarms, manual pull stations, and obvious physical damage without agent discharge.

Semiannual maintenance is required for dry chemical (NFPA 17) and wet chemical (NFPA 17A) systems, including agent, expellant, nozzles, and actuation checks.

Cylinder hydrostatic testing or requalification intervals depend on agent, cylinder type, and DOT/NFPA rules; record the test date on the cylinder tag.

Enclosure integrity testing verifies hold time and is repeated after enclosure, HVAC, or opening modifications, or at the interval required by the standard or AHJ.

Foam proportioning tests measure concentrate percentage during flow; conductivity or refractivity methods confirm the design mix ratio.

Trip testing confirms deluge or pre-action valves open on detection and that alarms, interlocks, and shutdowns operate in the designed sequence.

Clean agent cylinder weight or pressure checks confirm agent quantity; a loss beyond the listed tolerance requires recharge or investigation.

ITM records must include date, system, test method, results, deficiencies, and corrective actions, and be retained as required by code or AHJ.

NFPA 2001: clean agent systems; NFPA 12: CO2 systems; NFPA 17: dry chemical; NFPA 17A: wet chemical.

NFPA 11: foam systems; NFPA 16: foam-water systems; NFPA 15: water spray; NFPA 750: water mist.

NFPA 72 governs detection, alarm, and notification; NFPA 70 governs electrical installation; NFPA 101 governs life safety egress.

Design documents include hazard analysis, agent quantity calculations, nozzle layout, pipe isometrics, detection layout, and sequence of operations.

Acceptance testing verifies listed components, cylinder weights, detection operation, alarm annunciation, discharge simulation, and interlocks.

Sequence of operations defines the order of detection, alarm, HVAC shutdown, door release, agent discharge, and equipment shutdown.

As-built drawings and O&M manuals must reflect installed conditions, including cylinder sizes, nozzle locations, pipe routing, and device addresses.

The AHJ approves the design and installation under the adopted code; listed equipment and manufacturer instructions are mandatory.